One
advantage for me of having a hobby like radio control models is that since wireless technology is used for
commanding the airplane, helicopter, boat, car, etc., any interesting application qualifies as a legitimate
topic for RF Cafe articles. Such it is for this video of an R/C Superhero (formally spelled "RcSuperhero") model
designed and built by Greg Tanous, of Portland, Oregon. The model shown is 78 inches tall, has a 47" wingspan
(armspan) weighs about 3.3 pounds, and is propelled by a high-power brushless motor that generates more than 5
pounds of thrust; that is why RcSuperhero is able to take off straight up. Carbon fiber spars are used to
stiffen the foam structure. Radio control is via a spread spectrum system that operates on the license-free 2.4
GHz ISM band (although a 72 MHz FM system would work equally well). According to Greg, RcSuperhero builds and
flies as easily as an advanced trainer. Plans and entire kits for this 78" tall version and a 57" tall version
can be ordered from his...<more>1/3/2012

Is
this the future of construction? In this video, wirelessly controlled flying robots carry building blocks to the
work site and, after precisely positioning the block, plunks it into place. It then flies off to pick up and
place the next block. Multiple builder bots are in operation simultaneously. A 20-foot tall model (1:100) of a
modularized human habitat structure - a "vertical village" - was constructed automatically using 1,500
polystyrene blocks. A sophisticated algorithm defined not just the construction sequence and geometry, but also
handled traffic patterns, collision avoidance with other vehicles and the structure itself, and maximized system
efficiency. ETH Zurich roboticist
Rafaello D'Andrea and architects Fabio Gramazio and
Matthias Kohler are the progenitors and implementers of this amazing demonstration. BTW, the hissing sound
in the background is a painter spraying the blocks white.12/6/2011

How
much does the Internet weigh? That is the question posed and answered in this video that has been making the
rounds in the last couple weeks. Vsauce's Michael, who has produced many really good science-related short
videos, explains how to calculate the weight of all the information residing on the Internet based on the weight
of electrons necessary to transport the data. The sum: 50 grams - about the weight of a strawberry. Those 50
grams worth of electrons represent an estimated 5 exabytes (5 million terabytes). Furthermore, Michael
calculates that all of the actual information contained in pictures, e-mail, websites (like this one), movies,
documents, etc., in terms of electron mass, would fit on the head of a pin. Of course in the condensed state all
information would be lost because it would have no structure, so the exercise is purely academic.
11/8/2011What
you are seeing is the automated production of contraband that could result in heavy fines and possible
imprisonment if sold here in the United States after January 1, 2012. It's not a meth lab or an unauthorized
replica of the iPhone 4. What is it, then? Website visitor Hugh P. sent me a link to this video showing the
production line for
Duro-Test's
(nope, I've never heard of 'em either) 100-W, 120-V incandescent light
bulbs. The ingenuity needed to conceive of and implement the machinery and controllers for as relatively simple
a product as a light bulb is utterly impressive. Note how robust everything is and that most of it is metal,
something maybe not expected for machinery that handles delicate glass shells and forms ultrafine filament
wires. This is the kind of skill that built the modern world and is the result of lots of trial and error,
success and failure. Capitalism motivated the business owners, engineers, managers, production workers, and
ultimately the salesmen to believe the effort would be worth it. They busted their posteriors. OWS rats thinks
all of this result of other people's work should be made available for free to them, most of whom have never
produced anything but the need for toilet paper. 1/10/2012

Cloaking
has been a big deal since Star Trek made the concept part of the household lexicon. This video demonstrates the
principle described in a paper titled, "Mirage
Effect from Thermally Modulated Transparent Carbon Nanotube Sheets." Per the paper, "The single-beam mirage
effect, also known as photothermal deflection, is studied using a free-standing, highly aligned carbon nanotube
aerogel sheet as the heat source. The extremely low thermal capacitance and high heat transfer ability of these
transparent forest-drawn carbon nanotube sheets enables high frequency modulation of sheet temperature over an
enormous temperature range, thereby providing a sharp, rapidly changing gradient of refractive index in the
surrounding liquid or gas." BTW, forest-drawn means a sheet of vertical nanotubes standing like trees in a
forest.12/13/2011

Even
if you have taken some pretty intense physics courses in college, this series of short videos (a minute long)
will really appeal to you. In a mesmerizingly primal manner, the lessons are conducted with a voice narrating
while a hand draws simple diagrams to compliment the story. I am amazed to witness how consistently each concept
is presented in utter simplicity - sort of a validation of Occam's razor. The first one I watched was on the
speed of light in glass, and why frequency stays the same even though the speed of light is lower in glass. The
explanation of distance measurement from a Special Relativity might surprise you from a time perspective that
you hadn't considered before. Check out similarly creative lessons on the Heisenberg Uncertainty Principle, the
arrow of time, Schrödinger's Cat, and many more.11/15/2011

Showmanship
can buy you a lot of publicity - the more extreme, the better. I remember when the ground fault circuit
interrupter (GFCI) was first introduced to the market, a VP of some manufacturer (GE?) grabbed a radio that was
plugged into a GFCI receptacle and jumped into a pool with it. He lived, and everybody trusted GFCIs forever
after.
ioSafe, maker of "disaster-proof hardware," adopted a
similar marketing strategy by subjecting its Go-Anywhere hard drive to the discharge of a 1 MV Tesla coil. In
this demonstration filmed by MSNBC, CEO Rob Morris narrates while an expendable employee dons a Faraday suit,
complete with a real bird cage for a hood, and holds the Go-Anywhere up to the Tesla coil to invoke its wrath of
fiery discharge. Reporterette Rosa Golijan then connects the HDD to her laptop computer to test whether it is
indeed immune to "thunder bolts" (her term). Oops, it didn't work. Rather than being an upset for the team
though, Mr. Morris proceeded to demonstrate his company's other forte - data recovery. He opened the HDD (no ESD
protection worn, BTW), connected an interface board, and was able to read the drive content. Watch the video to
see a surprise at the end.1/17/2012

It's the time of year once again where much of the world celebrates Christmas or Hanukkah either as religious or
happy secular holidays. So, every year I offer a collection of music videos that my family particularly enjoys,
especially ones with kids singing. Hopefully you will as well. In spite of politically correct efforts to
suppress and erase the traditions, here at RF Cafe I have never been one to yield to such bigotry. Don't be
offended; be tolerant. Merry Christmas to all, and to all a good night.
12/20/2011

If
the generals and insane leader of an unfriendly nation knew that the country they were provoking had the
capability to drop a significant tonnage of explosives on their heads in an hour or less, would that serve as a
deterrent? News wires recently reported on a successful test of the USAF's Falcon Hypersonic Technology Vehicle
(HTV) that has such a potential. The first test a couple months ago ended in failure, but evidently the kinks
have been worked out. According to DARPA's website, "Falcon HTV-2 is an unmanned, rocket-launched, maneuverable
aircraft that glides through the Earth’s atmosphere at incredibly fast speeds—Mach 20 (approximately 13,000
mph). At HTV-2 speeds, flight time between New York City and Los Angeles would be less than 12 minutes. The
HTV-2 vehicle is a 'data truck' with numerous sensors that collect data in an uncertain operating envelope."
<more>11/22/2011

The
Japanese have been way ahead of the curve in the robot world for many years. Combining autonomy with wireless
control has led to this "Spherical Flying Machine" that was demonstrated by the Japan Ministry of Defense.
Beginning with a dose of theatrical showmanship, the mystery craft jumps out of a round Styrofoam container
after the lid is suddenly popped off. What emerges is a very obviously highly stable and maneuverable sphere
that effortlessly floats above the stage and audience, while intermittently flitting about like a dragonfly
moving along the shoreline from cattail to cattail. Multiple onboard gyroscopes provide attitude control and
stability so effective that even after being hit or pushed, it rights itself. Flying is not its only method of
locomotion; once on the ground the spherical flying machine becomes the spherical rolling machine. It can also
hug a wall near the ceiling and navigate through a building. This allows it to be used for surveillance in
almost any environment. Its quite electric motors, most likely powerful, microprocessor-driven brushless models
given life by high-C lithium polymer batteries, provide plenty of motivational force. A 2.4 GHz radio control
system was used for guidance. Come to think of it,...<more>1/24/2012

"A
Ham's Night Before Christmas," by Gary Pearce, KN4AQ, was first posted on YouTube in November of 2011. This
clever adaptation of Clement Clark Moore's familiar story Twas the Night Before Christmas. The
narration is accompanied by pictures of vintage magazine covers, advertisements, and cartoons. It opens with the
cover of the December 1920 edition of QST (first edition ever printed was December of 1915). Here are the first
couple verses, as discovered on
Brainerd Area Amateur Radio Club
website. Please visit them for the rest of the poem, as well as other versions written by various authors. All
are very clever. <more>12/27/2011

As
with amateur radio hobbyists who continually help advance the state of the art in electronics, software, and
communications, so too do model aircraft hobbyists help push back the frontiers of ignorance in their realm.
Guys like Tom Mast, a Staff Engineer with Bell Helicopter Textron, are part of a fairly elite cadre of people
with an ability to integrate a large collection of skills into a single sophisticated project. Knowledge of
rotorcraft and fixed wing aerodynamics, propulsion system mechanical and electrical requirements,
microcontroller programming, structure weight-strength tradeoffs, materials science, design-for-production
aspects, and the skill to fly both fixed and rotor wing models were necessary to pull this off. I have not found
any detailed history on the development, but about three years of dedicated effort was required from concept to
reality. As you can <more>11/29/201

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling
2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas
and reference material while performing my work as an RF system and circuit design engineer.
The Internet was still largely an unknown entity at the time and not much was available
in the form of WYSIWYG
...

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